Portable computers have revolutionized the way in which one works by allowing far greater flexibility in where one works. The ever decreasing size of computers has resulted in ever increasing flexibility. Notebook and sub-notebook computers now allow one to take a computer with them virtually anywhere. Advanced battery management techniques allow portable computers to be used for extended periods of time without external power.
Connectivity products have been no less revolutionary. One can improve flexibility and efficiency by connecting his computer to printers, plotters, modems, trackballs, mice, local area networks, optical disk drives, image scanners, and many other peripheral devices.
However, connectivity and mobility are rarely compatible. The need to disconnect and reconnect many external devices significantly reduces ones ability to grab these tiny computers and to run with them.
There have been several attempts to create a system where multiple devices can be connected and disconnected in a single action. One such system is described in U.S. Pat. No. 5,123,092 to Buxton et al. The Buxton et al. patent describes an expansion box that provides for peripheral connections. The expansion box also provides space for industry standard desktop PC circuit boards that will not fit into a small portable computer. The expansion box disclosed in the Buxton et al. patent can be quickly connected to and disconnected from a portable computer with a single connector.
However, such an expansion box is quite complex and expensive. It has its own power supply and circuitry to handle contention between devices in the computer and devices residing at the same bus address in the expansion box.
Every device in a computer has an address. If you provide a serial port on a computer and a second serial port having the same address in a connected expansion box, special circuitry is need to prevent conflicts between these two ports. The expansion box disclosed in the Buxton et al. patent provides such circuitry.
Another approach to the problem is disclosed in U.S. Pat. No. 5,030,128 to Herron et al. The Herron et al. patent discloses a docking module that provides connectors aligned with corresponding connectors on the back of a portable computer. The connectors can be connected and disconnected simultaneously by connecting and disconnecting the docking module. The docking module also provides duplicate connectors for the connection of peripheral devices. These duplicate connectors are wired straight through to the connectors connected to the computer. The docking module disclosed in the Herron et al. patent is a passive device, and it is therefore less expensive than the expansion box disclosed in the Buxton et al. patent.
However, it is not a single connector like the expansion box disclosed in the Buxton et al. patent. In the docking module, each connector is reproduced between the docking module and the computer causing a significant amount of resistance to making a connection. The docking module further requires precise alignment of multiple connectors on the docking module and computer. A lever arrangement is provided to exert enough effort to connect the docking module to the computer. If the alignment is not exact, the connection force can cause damage to the connectors.